ANSI FN class fitting 2

[kakalee1]

I have a question about press fitting plastic part. On the drawing, the customer calls out for a fit per ANSI B4.1 FN2. The parts are both made from plastics (Vespel). Would it be appropriate to use the tolerance limits from table 11. ANSI Standard Force and Shrink Fits? The customer doesn't specify the tolerance for the piece part. They only call out the nominal diameter and the type of fit.

I always thought that table is calculated for steel parts only.

Thanks,

NL

 

[3DDave]

They called out all that is required: the spec; the FN2 fit class; and the nominal diameter allow finding the tolerance(s.)

The table may have steel parts in mind, but that doesn't affect the interpretation. If they have determined that the fit is applicable to their task they can certainly use it. Without any further information it isn't possible to tell if they are correct.

 

[drawoh]

kakalee1,

You can warn the customer that a press-fit with plastic probably is not permanent, like it would be with steel. Given that they are calling out an FN2 fit rather than an FN1 makes me think they know this. Still, it prevents stuff from bring rejected by their QA.

--
JHG

 

[kakalee1]

Thanks for the answers